Polyamide containing beta carbonamido-alpha-aminopropionic acid units



Patented Sept. 15, 1953 POLYAMIDE CONTAINING BETA CARBON- AMIDO ALPHA 7'A INoPRoPIoNro non) UNITS Maynard S. Raasch and Charles W. Tulloek,Wilmington, Nemours DeL, assignors to E. I. du Pont. de & Company, Wilmingtcn, DeL, a corporation of Delaware No Drawing. Application August18, 1950, Serial No. 180,319

24 Claims. (01. 250-175) This invention relates to new condensationpolymers. More specifically, it relates to new alpha-amino acidpolyamides.

Hitherto the many different types of alphaamino'acid polyamides andcopolyamides thus far known to the art, for example the relatively highmolecular weight film-forming alphaamino acid copolyamide prepared byWoodward and Schramm [J. Am. Chem. Soc, 69, 1550 (1947)] and the highmolecular weight alphaamino acid copolyamides of unique solubility Tproperties prepared by MacDonald (Serial No.

'778,458, flled August 5, 1947) by copolymerizing the N-carboanhydridesof alpha-aminocarboxylic acids containing at least one hydrogen on thealpha-carbon are either highly water insoluble and water insensitive .orelse water soluble but extremely hy roscopic. Examples of the lattertype of polyamides include those containing high proportions oi combinedN-substituted, i. e., alpha-secondary amino acid units. Such polyamides,although sufiiciently water soluble to per- Init their use as silverhalide binders in photographic film, are so hygroscopic, i. e.,sensitive to water vapor, as to make the storage of films preparedtherefrom impossible except under the most highly controlled conditionsof dryness.

This invention has as an object the prepara-.- tion of newalpha-monoaminomonocarboxylic acid polyamides. A further object is thepreparae tion of nonhygroscopic but water soluble or at least watersensitive alpha-.monoaminomonocarboxylic acid polyamides. Other objectswill ap-. pear hereinafter. These objects are accomplished by theinvention of synthetic, optically inactive alpha-amino acid polyamidescontaining a plurality of com-. bined alpha;carbonamidomethylglycineunits, 1,, e., beta-oarbonamido-alphaeaminopropionic acid units, whichare surprisingly highly, water soluble or water sensitive and at thesame time nonhygroscopic. Included in the products of this invention arethose polyamides containing combinedbeta-carbonamido-alpha-aminopropionic acid units wherein one valence ofthe extralinear amide nitrogen is utilized in forming the amide link andthe remaining two valences are satisfled by hydrogen, or hydrocarbonradicals, e. g., alkyl, cycloalkyl, aryl, or aralkyl radicals. Theextralinear amide nitrogens can also be members of a 5 to '7, andpreferably 6, membered heterocycle in which case there can be otherheteroatoms, i. e., oxygen, nitrogen or sulfur, inthe hete'rocycle.Particularly preferred polyamides of this invention are those whichcontain, in addition to the above-describedbetaecarbonamidoalpha-,aminopropionic acid units, combined beta.-carboalkoxyor carboaralkoxyalpha-amino: propionic acid units.

, The polyamides or this invention possess extralinear carbonamido andsubstituted carbonamido groups and are capable of ready modificationthrough chemical reactions applied thereto. Such modifications, forinstance, conversion of the extralinear carbonamido groups to nitrilegroups and the controllable crosslinking of the polyamides throughreaction of the extralinear carbonamido groups with formaldehyde orother methylol compounds are particularly efficacious in achieving manydesired goals, for instance,

modifying the organic solubilities of the poly: amides.

. The polya des of thi in e ion can be nveniently prepared bypolymerizing the amide.- f orming derivatives of beta-carhamyle andbeta.- substituted carbamyl alpha aminopropionic acids with or withoutthe amide-forming derive atives of other alpha-aminocarboxylic acids.The most convenient way of preparing the poly.-

' amides containing both combined beta-carbonamido and substituted betacarbonamido: alpha-aminopropionic acid and beta-carboalkoxy rb ara xy heminopropionic d un ts 15 9 l mer z the ami o m derivatives ofbetaecarboalkoxyor carboaralkoxy alpha-aminopropionic acids with theamideforming derivatives of other alpharaminocare boxylic acids,preferably alpha monoaminomonocarboxylic acids, ii desired, and to reactthe thus formed polymer with ammonia. or the requisite primary orsecondary amine needed to convert the extralinear carboalkoxy or carbo:aralkoxy groups to the desiredcarbonamido or s stitute -qa enam d rou sThese a monia and/oramine reactions can be conveniently carried out atroom temperature or slightly higher, preferably in solution ordispersion in an inert, liquid reaction medium. Among the knownamide-forming derivatives of the alpha-amino acids, including thebetaecarboalkoxyor carboaralkoxyealpha-aminopropionic acids, it ispreferred to use the N-carboanhydrides since they can conveniently beprepared in good yields from readily available materials and are capableof being easily polymerized with evolution of carbon dioxide to high.molecular weight filmand fibfireforming alpha-amino acid polyamides.

- The following examples in which the parts given are by weight aresubmitted to further illustrate this invention. As used in theseexamples, inherent viscosity, 1111111., is defined by the followingformula:

Zn "rel.

C wherein In is the natural logarithm,

1 solution 1, solvent 1 being viscosity and C is concentration of thesolute in grams per 100 cc. of solution. The 'fllnh.

values given in the following examples, unless EXAMPLE I PartA.Preparation of DL-beta-carbomethoxyaZpha-aminomopionic acidhydrochloride (Prepared according to the method of Pfeiffer andChristeleit, Z. physiol. Chem. 245, 205 (193'?) for the preparation ofL-aspartic acid monoethyl ester.)

A vigorous stream of gaseous hydrogen chloride is passed into a solutionof 80 parts of DL- beta-carboxy-alpha-aminopropionic acid in 634 partsof reagent-grade methanol with stirring over a period of 33 minutesunder anhydrous conditions. During this time the temperature of thereaction mixture rises from 25 to 53 C. At the end of this period, themixture is cooled to 2 C. with an ice/water bath and dry hydrogenchloride again added with stirring for 20 minutes during which time thereaction mixture warms up to C.; the ice bath is left in place duringthe second addition of the dry hydrogen chloride. The crudebeta-carbomethoxy-alpha-aminopropionic acid hydrochloride isprecipitated from the resulting clear solution by the addition of 3210parts of anhydrous diethyl ether. The precipitate is removed byfiltration and air dried. There is thus obtained 105 parts (95.5% yield)of DL-beta-carbomethoxy-alpha-aminopropionic acid hydrochloride. Thishydrochloride is recrystallized by dissolving in 554 parts ofreagentgrade methanol, adding 2565 parts of anhydrous diethyl ether, andcooling the resulting suspen- 'sion at 3 C. overnight. The product isremoved by filtration and after drying at 25 C. for several hours, thereis finally obtained 66 parts (59.8% yield) of purifiedDL-beta-carbomethoxy-alphaaminopropionic acid hydrochloride as whitecrystals melting at 193 to 194 C.

Analysis Calculated for C5H10NO4C12 N, 7.63%. Found: N, 7.53%.

Part B.Preparati0n of DL-beta-carbomethoxyalpha-aminomopionic acid N-carb0anhydride A suspension of 101 parts of the aboveDL-betacarbomethoxy-alpha-aminopropionic acid hydrochloride in 1500parts of purified, anhydrous dioxane in a reactor fitted with anefficient stirrer, a reflux water condenser, and a gas inlet tubeconnected to a source of gaseou phosgene and so placed that its lowerextremity is just above the surface of the suspension is treated withgaseous phosgene for '75 minutes while maintaining the temperature ofthe reaction mixture between 70 and 81 C. at such a rate that an excessof phosgene is added. At the end of this time the reaction mixture isfiltered to remove unreacted starting material (which amounts to 7.5parts) and dioxane is removed from the filtrate by distillation under apressure corresponding to -40 mm. of mercury using a water bath at 49-53C. After approximately 95% of the dioxane has been removed, theremaining syrup is taken up in 26 additional parts of dioxane and againfiltered to remove any small traces ofDL-beta-carbomethoxy-alpha-aminopropionic acid hydrochloride and 321parts of anhydrous diethyl ether added to the filtrate. About 5 parts ofa brown syrup separates and is removed by filtration; '71 additionalparts of diethyl ether are added and the mixture cooled in an ice waterbath. On filtration there is thus obtained 64 parts (58.0% yield) ofwhite crystalline DL-beta-carbomethoxy-alpha-aminopropionic acidN-carboanhydride-1/2 dioxane.

This product and those from two other similar I runs are combined togive 229 parts of crude N- carboanhydride' l/2 dioxane adduct. Thuscrude N-carboanhydride-l/Z dioxane adduct is recrystallized bydissolving in 775 parts of purified, anhydrous dioxane, adding 963 partsof anhydrous diethyl ether, rapidly filtering to remove the firstcrystals forming, which are slightly colored, cooling in an ice waterbath and removing the resultant precipitate by suction filtration. Afterair drying, there is obtained 186 parts of once purifiedN-carboanhydride-l/Z dioxane adduct. This recrystallization is repeatedand there is finally obtained 133 parts (58.0% recovery) of twicerecrystallized DL-beta-carbomethoxy-alpha-aminopropionic acidN-carboanhydride-l/2 dioxane adduct as white needle crystals melting at64 to 66 C. (inserted in bath at 50 C. and raised to temperature)Analysis Calculated for CsI-InOsN: c, 44.24%; H, 5.07%:

N,6.45% Found: c, 44.44%; H, 5.32%; N, 6.49%

A 1.87 part sample of the above beta-carbomethoxy-alpha-aminopropionicacid N-carboanhydride-l/2 dioxane is dissolved in 131 parts of boilinganhydrous diethyl ether and the small amount of insoluble materialremoved by filtration. To the filtrate is added 66 parts of petroleumether (boiling range 30-60 C.) and the resulting mixture cooled to roomtemperature. The solid that separates out is removed by filtration.There is thus obtained 0.6 part of crystalline material melting at 82-84C. with decomposition (inserted in melting point bath at 50 C., andraised to temperature). Another sample of crystalline material similarlyobtained melting at 83-85 C. with decomposition when inserted in thebath at 50 C. and raised to temperature is found by analysis to be thepure DL-beta-carbomethoxy-alpha-aminopropionic acid N-carboanhydridefree of any dioxane or diethyl ether of crystallization.

Analysis Calculated for CaH'zOsNI C, 41.62%; H, 4.05%;

N, 8.09% Found: C, 41.65%; H, 4.21%; N, 8.30%

Part C.Preparation of poly-DL-beta-carbometi zoxy-aZpha-aminopropionicacid by polymerizatz'on of the corresponding N-carboanhydride assessed.

and refluxing at atmospheric pressure under anhydrous conditionscontinued for 2.2 days: Dar ing this time the polymer separates out ofthe polymerization mixture. as a light, white, powdery precipitate,which exhibits an inherent viscosity- At the end of this time, theinsoluble polyamide is removed from the polymerization mixture anddissolved in chloroform at a solids concentration of 6.3% by weight.The. resultant, clear, viscous solution is flowed in a thin film onto aglass plate and the chloroform allowed to evaporate at. room,

temperature. After further drying at 60 C. for two hours, there istough, self-supporting film of the homopolyamide fromDL-beta-carbomethoxy-alpha aminopros,

pionic acid which is soluble in tetrachloroethane, m-cresol, formicacid, and dimethylformamide. Samples of this film exhibit a tenacity of11.150 lb./sq.in. and 3.2% elongation, a modulus of; still ness of 3.9lb./sq.in., a pliability factor of 2.6, an average water absorption of8.03% by weight when going from 0 to 100% relativehumidity, and amelting point of 170-175 C. Samples of this film (approximately 6 milsthick), after being softened in water at 70 C., can be readily oriented.Extensions of 119 to 144% can be obtained by this treatment and suchoriented films exhibit tenacities as high as 29,500 lb./sq.in. andelongations as high as 21%. Further samples of this homopolyamidesimilarly prepared of 77inh.=.51 when wet-spun from chloroform solutioninto a methanol coagulating bath yield a yarn of 40.9 denier, exhibitingtenacities as high as 0.6 gram per denier and elongations of 1.5%. 1

Part D.-Preparation of a copolyamide from DL-beta-carbamyl-aZpha-aminopropionic acid/ DL-beta carbomethoxy alphaaminopropi- (mic acid A two-part sample of a polyamide from DL-beta-carbomethoxy-alpha-amin0propionic acid (prepared as described aboveand of mnh,=. 0.28)'

is suspended in 82 parts of liquid ammonia containing 0.5 part (25.0% onthe basisof the polymer) of ammonium chloride catalyst in a Dewar flaskfor three days at room temperature.

At the end of this time, the unreacted liquid ammonia is removed fromthe reaction mixture by evaporation at room temperature. The m. moniumchloride is removed from the 0013 119? amide residue by repeated waterwashings'until a negative chloride test is obtained from :the.

washings. Nitrogen analysis of the waterwashed residue indicates thepolyamide to contain 22.73% nitrogen. The theoretical valuefor completeconversion of all the extralinear carbomet oxy roups to carbamyl groups(i.:e;, a polyamide of molecular formula C4HsNz02) is 24.60% nitrogen.These results indicate the product to be an 86/14 copolyamide from DL-beta-carbamyl-alphaaminopropionic acid/DL'beta-carbomethoxy-alpha-aminopropionic acid. The copolyamide is clearand brittle in film form and is soluble in warm water and formic acidbut insoluble in benzene, dioxane, methanol, acetone, ethyl acetate,dimethylformamide, chloroform and m-cresol, all solubilities being atsteam-bath temperatures. The copolyamide exhibits an obtained a clear,strong,

'i]lnh.=0.53 in formic acid at 25 C. at a concentration of 0 .3 g. per100 cc.'of solution and softens;

(prepared as described; above and of mnh.=0.56)'

is added portionwiseofver a period of 2 to 3 min utes to a gentlystirred solution of 50. parts of water and 9 parts of aqueous ammoniumhy-. droxide- (28% ammonia) at room temperature. The resulting solutionis allowed to stand for one. hour at room temperature and is thenfiltered to remove small traces of impurities. The filtrate is'poured ina thin film onto a glass plate and the water and unreacted ammoniaallowed to evaporate atroom temperature. A clear, self supporting butbrittle film of the copolyamide is thus obtained. Nitrogen analysis ofsamples of this film indicate the copolyamide to contain 21.16%nitrogen. The theoretical value for complete conversion of all theextralinear carbo-. methoxy groups to. carbamyl groups (i. e., apolyamide of molecular formula C4H6N2Q2) is 24.60% nitrogen. Theseresults indicate the product tobe a /25 copolyamide from DL-beta-carbamyl-alpha aminopropionic acid/DLF.beta-earbomethoxy-alpha-aminopropionic acid. Thoicopolyamide is, solublein water and formic, acid but insoluble (at steam bath temperatures) inchloroform, methanol, m-cresol, and dimethyl-, formamide: Thecopolyamide exhibits inherent viscosities of 0.37 in formic acid, 0.54in dischloroacetic acid, and 2.69 in water, all at a concentration of0.3 g. of copolyamide per cc. of solution at 25 C.

A .one partsample of an 87/13 copolyamide from.DLi-beta-qarbamyl-alpha-aminopropionic acid/DL-beta carbomethoxy alphaaminopropionio acid (prepared in general as desscribed aboveinExample I,Part D and of 'qinh.,=0..34: in

formic acid at a concentration of 03 g-,/ 100 cc. of solution at 25 C.)is dissolved in 6.1 parts of formic-acid and 2.2 parts of 37% aqueousformals dehyde solution and the resulting mixture allowed to stand at 25C. for five minutes with stirring. The clear gel so obtained is washedWell with water and air dried. This copolyamide is soluble in hot waterfrom whi h clear. t gh. films can becast. After heating at C. for twohours, the composition is no longer water soluble.

-.A one-part sample of the same 87/13 copolyamide is dissolved in 10parts of water; 0.04 part of a 87% aqueous formaldehyde solution isadded and the reaction mixture evaporated to dryness on a steam bath. Abrittle, self-supporting film of the polymer product is obtained whichis solubl'eJ i'n 'Warm water and dichloroacetic acid.

After heating at 120 C. for two hours, the sample is still watersoluble. EXAMPLE II Part 4;-DL-beta-MN-dimethylcarbamylealpha-'r-aminopropionic acid/11L beta-carbome-thory alphmominopropionic acidcopolyamide YApne-part sample of a polyamide from DL- beta carbomethoxyalpha aminopropionic acid (prepared in general as described in ExampleI, Part C and of 1 )lnh.=O-51) is dissolved in 8.5 partsofdlmethylformamide and the solution allowed to stand at roomtemperature for 26 .days under extralinear carbomethoxy groups toN,N-dimethylcarbamyl groups (i. e., a polyamide of molecular formulaCsHN202) is 19.72% nitrogen. These results thus indicate the product tobe an 18/82 copolyamide from DL-beta-N,N-dimethyl-.carbamyl-alpha-aminopropionic acid/DLbetacarbomethoxy-alpha-aminopropionic acid. The copolyamide is ble informic and dichloroacetic acids, mnh.=0.47 in formic acid. Part B Aone-part sample of a polyamide from DL- beta-carbomethoxy-alphaaminopropionic acid (prepared in general as described in Example I, PartC and of 71inh =0.56) is dissolved in 23.7 parts of dimethylformamideand the reaction mixture allowed to stand at room temperature for hoursunder anhydrous conditions. At the end of this time, the reactionmixture is heated to 82 C. for 1.5 hours. The clear solution is thenpoured into an excess of anhydrous diethyl ether, the resulting mixtureallowed to stand at room temperature for 24 hours, and the solid productremoved by filtration under anhydrous conditions. The solid copolyamideproduct is then dried at 95 C. in a vacuum oven for four hours. Theresultant, white solid copolyamide is soluble in chloroform, from whichsolutions, clear, self-supporting films may be cast. Nitrogen analysisindicates the copolyamide product to contain 11.09% nitrogen. The.theoretical value for complete conversion of the extralinearcarbomethoxy groups to N,N-dimethylcarbamyl groups (1. e., a polyamideof molecular formula CeHmNzOz) is 19.72%nitrogen. The theoretical valuefor the starting DL-beta-carbor'nethoxyalpha-aminopropionic acidpolyamide is 10.85% nitrogen. These results thus indicate the product tobe a 2.7/97.3 copolyamide from DL-beta- N,N dimethylcarbamyl alphaaminopropionic acid/DL-beta-carbomethoxy alpha aminopropionic acid.

This copolyamide is surprisingly much more water sensitive than thestarting DL-beta-carbomethoxy-alpha-aminopropionic acid polyamide. Forinstance, films of the starting homopolyamide, cast from chloroformsolution, can be most readily lifted from the casting surface in filmform by first being soaked in water. During this soaking process, novisiblechange occurs in the nature of the film nor is any change noticedafter the film has been removed and dried.

On the other hand, films of the above 2.7/97 .3 DL-betaN,N-dimethylcarbamyl-alphaaminopropionicacid/DL-beta-carbomethoxy-alpha-aminopropionic acid copolyamide castfrom chloroform solution are softened so much by being soaked in waterthat it is impossible to remove the soaked material in film form. Infact, attempts to do so result in the formation of continuous filamentsof the copolyamide. In other words, the film becomes so softened thatunder any applied stress, e. g., lifting, it loses its film shape andactually flows in response to the stress. Effectively, the, watersoftened and swollen film of the copolyamide is spun intocontininsoluble in chloroform but so1u-.

8. uous filaments by such .aprocess. ments upon drying retain theirshape and dry as strong, self-supporting, continuous filaments. Duringthe water soaking, films of this copolyamide in water soften and swellbut also become noticeably opaque.

Part C Aten-part sample of the same polyamide from DL-beta-carbomethoxyalpha aminopropionic acid used in Example II, Part A, is dissolved in71.8 parts of dimethylammonium dimethylcarbamate, the resulting solutionrefluxed for two hours, and 20.5 parts additional dimethylam-' moniumdimethylcarbamate added. The reaction mixture is then allowed to standat room temperature for two days under anhydrous conditions, warmed foran additional four hours on a steam bath, and finally allowed to standat room temperature for an additional day. At the end of this time theunreacted dimethylammonium dimethylcarbamate is removed from thereaction mixture by warming on a steam bath in a stream of air. Theresidue is washed with diethyl ether and warmed in a vacuum oven at C.for four hours. The resulting polyamide residue is found by analysis tocontain 18.06% nitrogen. The theoretical value for complete conversionof the extralinear carbomethoxy groups to N,N-dimethylcarbamyl groups(i. e., a polyamide of molecular formula Gel-N202) is 19.72% nitrogen.These results indicate that the polyamide product is an 81.13/18copolyamide from DL-beta N,N-dimethylcarbamyl alphaaminopropionicacid/DL-beta-carbomethoxy-alpha-aminopropionic acid. This copolyamide issoluble in water, 2-B alcohol, chloroform, formic acid, m-cresol anddimethylformamide. Clear, self-supporting films can be obtained by filmcasting from solutions in these solvents,-for instance, from water. Thecopolyamide exhibits an mn.=0.23.

EXAMPLE III Part A.-DL-beta-N n butylcarbamyl alphaamz'nopropiomcacid/DL-beta carbomethoazyalpha-aminopv'opionic acid copolyamid Atwo-part sample of a polyamide from DL- beta carbomethoxy-alphaaminopropionic acid (prepared in general as described above in ExampleI, Part C and of 1 1nh.=0.49) is suspended in a mixture of 7.4 parts ofn-butylamine and 50 parts of water and stirred at room temperature forone hour. The water and unreacted n-butylamine are removed from thereaction mixture by evaporation at room temperature. The resultingpolyamide is found by analysis to contain 14.68% nitrogen. Thetheoretical value for complete conversion of the extralinearcarbomethoxy groups to N-n-butylcarbamyl groups (i. e., a polyamide ofmolecular formula Cal-113N202) is 16.57% nitrogen. These results thusindicate the polyamide to be a 67/33 copolyamide fromDL-beta-N-n-butylcarbamyl-alpha-aminopropionic acid/DL-betacarbomethoxy-alpha-aminopropionic acid. The copolyamide is soluble inwater, m-cresol, methanol, formic acid, and dimethylformami'de.

..PartB hours and finally in a vacuum oven at 85 4.5 hours.

CsH13N202) is 16.57%.

picnic acid.

. groups (1. e., a

C12H22N2O2) is 12.39%

winopronpionic acid.

nitrogen.

addition of the amine and the mixture is warmed is allowed to stand atroom temperature for 12 days, and the cloro'fo'rm then removed bywarming on a steam bath for th;ee C. or There is thus obtained 13 partsof a polyamide residue exhibiting an 1mm. of 0.11. Nitrogen analysisindicates the product to contain 15.32% nitrogen. The theoretical valuefor the complete conversion of the extralinear carbomethoxy groups toN-n-butylcarbamyl groups (1. e., a polyamide of molecular formula Theseresults show that the product is an 80/20 copolyamide from DL- beta N-nbutylcarbamyl-alplia-aminopropionic acid/DL betacarbomethoxy-alpha-aminopro- EXAMPLE IV DL-beta-N,N-DI n-butyZcuirbtmz ll-alpha-aminopropionic acid/BL-beta-oarbomethoxy-alphaaminopropionicacid copolyamide Ten parts of a polyamide fromDL-beta-earbomethoxy-alpha-aminopropionic acid (prepared as describedabove in Example I, Part C and or" mnh.=0.52) in 297.8 parts ofchloroform is heated at the reflux with 23 parts of di-n-butylamine for0.33 hours. The clear fluid solution is allowed to stand at roomtemperature for 22 days. The resulting gel is cut up, air dried, andwarmedin a vacuum oven for fiv hours at 85 C. to remove any unreactedamine and chloroform. Nitrogen analysis of the approximately 10.5 partsor residue thereby obtained indicate this product to contain 1 2.07%nitrogen. The theoretical value for complete conversion of theext'r'alinear carbomethoxy groups to N,N-din-butylcarbamyl polyamide ofmolecular formula not is shown to be a 79/21 copoly'am'ide from DL-Lbeta N,N-di-n-butylearbamyl alpha-aminopropicnic acid/DLbeta-carbomethoxy-alpha-an1- This copolyamide is soluble in water,formic acid, m-cresol, dimethylformam- -id'e and methanol.

EXAMPLE .V

.DL betu- (4-morpholinecarbonyl)-aZphu-ami1zoline is heated at 100hydrous conditions.

.-unreacted' morpholine is removed by repeated diethyl. ether washesuntil the morphol'ine order is gone and the product then air driedovernight. Analysis of the polyamide residue thereby obtained indicatesthe product to contain 13.85% The theoretical value for completeconversion of the extralinear canbomethoxy groups to morpholinecarbonylgroups (,i.- e., a

"polyamide of molecular formula CaHmNzOa) is 15 22% nitrogen. Theseresults indicate the -of 0.21 and issoluble in chloroform, formic acid,-m-cresol and 'dim'ethylformami'de and softens on a copper block at 204-and slowly decomposes with browning at 270 C. i

nitrogen. Thus, the prod-,

Q 1.80, and a decomposition temperature of 215C.

C. but insoluble I elongation of 2.64%,

10 EXAMPLE VI Part Ar -Reaction of the polyamide from D13- betacarbomethloscy 1 alpha ammopropiortic acid with hemamethyieiiedzdmine Asolution is prepared by dissolving 2 parts of a polyamide fromDLbeta-carbomethoXy-alphacrate at room temperature. The resulting filmis then baked at C. for 40 minutes. At the end of this time, solubilitydeterminations indicate the resulting film to be no longer soluble inchloroform, thereby indicating the crosslinking effected through thereaction of the hexamethylenediamine with extra-linearcarbomethoxymethyl groups in neighboring polymer chains, i. e., theformation of hexamethylene-bis-carbonamidomethyl crosslinks between thepolymer chains. The polymer is also insoluble at 100 C. in formic acid,dichloroacetic acid, m-cresol and di-rnethylformamide -in all of whichsolvents the starting polyamide is soluble. V

Nitrogen analysis of this chloroform-insoluble copolyamide indicatesthecopolyamide to contain 11.06% conversion of 2.9% of the originalextralinear carbomethoxymethyl groups in the starting polyamide to theabove-described hexamethylenebis-carbonamidomethyl crosslinks. Filmsamples of this polyamide exhibit an average tensile strength of 10,095Ila/sq. in., an average elongation of 2.71%, an average pliabilityfigure of An additional experiment carried out under the same conditionswith further samples of the same batch of polyamide from DL-beta-carbo-'methoxy alpha-aminopropionic acid varying only in that 0.0392 part of.hexamethylenediarn'ine is added (4.36% of the theoretical amount ofhexamethylenediamine needed .to react with all the extralinearcarbome'thoxy groups) produces a polyamide which is soluble in m-cresolat 100 (at the same temperature) in chloroform, formic acid,dimethylformamide, and dich'loroacetic acid-in all of which solvents thestarting DL beta earbomethoxy alphaam'inopropionic acid polyamide issoluble. Film samples of this polyamide exhibit an average tensilestrength of 9522 lb./sq. in., an average an averag pliability figure of1.91, and soften at C. Nitrogen analysis carried out on the copolyamideproduct is not sufficiently accurate nor reproducible to enable anabsolute determination of the relative percentage of the extralinearcarbomethoxymethyl groups in the starting beta-.carbomethoxy-alpha-aminopropionic acid polyamide which have beenconverted into hexamethylene bis(carbonam'idomethyl) crosslinks throughreaction with the hexamethylenedibis(carbonamidomethyl crosslinks. Thdifierences in solubilities already pointed out indicate that some ofthese crosslifnks "have been -i'orrne'd. Furthermore;

nitrogen which corresponds to the in view of the I Part A, wherein Imethylene Part B.-Reaction of the polyamide from amide is soluble. perblock curl and become brittle at, 250 C. and

.11 preceding experiment described in Example VI,

reaction with 10.9% of the hexamethylenediamine theoretically needed toreact with all the extralinear carbomethoxymethyl groups, yields aproduct, which, by analysis, is indicated to have 2.9% of the startingcarbomethoxymethyl groups converted tohexamethylenebis(carbonamidomethyl) crosslinks, the example, carried outunder the same conditions but using only 4.36% of the amount ofhexamethylenediamine theoretically needed to react with all theextralinear carbomethoxymethyl groups would yield a product whereinabout 1.2% of the hexabis(carbonamidomethyl) crosslinks have beenformed.

DL- beta carbomethoxy alpha aminopropionic acid with ethylenediamine Asolution is prepared by dissolving 2 parts of the polyamide from DL betacarbomethoxyalpha aminopropionic acid (prepared as described above inExample I, Part C and of -1;1nn.:0.540.56) in 59.6 parts of chloroform.A

' parts of chloroform is then added. After thorough mixing the reactionmixture ispoured in a thin film onto a glass plate and the chloroformsolvent allowed to evaporate at room temperature. The resulting film,after being baked at 105 C. for 40 minutes, is insoluble (at steam'bathtemperatures) in chloroform, dimethylformamide, formic acid, m-cresol,and dichloroacetic acid-inall of which solvents the starting poly-Samples of the film on a copmelt at 265 C. with decomposition. Samplesof the film exhibit average tensile strengths of 9284 lbs/sq. in.,elongations of 3.24%, pliability figures of 2.44, and an average waterabsorption of 14.5%. Nitrogen analysis of the insoluble copolyamideindicates it to contain 11.91% nitrogen which corresponds to theconversion of 9.5% of the original extralinear carbomethoxymethyl 1groups in the starting polyamide to ethylene-biscarbonamidomethylcrosslinks.

An additional experiment carried out under the same conditions varyingonly in that 0.051

part of ethylenediamine is added (10.96% of the theoretical amount ofethylenediamine) produces a polyamide insoluble (at steam bathtemperature) in chloroform, dimethylformamide, formic acid,dichloroacetic acid and m-cresol in all of p which solvents the startingDL-beta-carbomethoxy-alpha-aminopropionic acid polyamide is soluble.Nitrogen analysis of this copolyamide indicates it to contain 11.22%nitrogen from which it is calculated 3.3% of the extralinearcarbomethoxymethyl groups have been converted to ethylene biscarbonamidomethyl crosslinks.

Film samples of the copolyamide exhibit average tensile strengths of10,354 lbs/sq. in., elongations of 2.9% and pliability figures of 1.76.and decomposed with gas evolution at 245 C.

EXAMPLE VII Preparation of a copolyamide from DL-beta- (hy- {Anothertwo-partsample bf the same poly- 'amide from DL beta carbomethoxya1pha-,;;:p5 added to the resultantv yellow. gelatinous mass.

aminopropionic acid described in the preceding example is addedportionwise over a period of-two to three minutes to a solution of 10.2parts of ethanolamine in 50 parts of water. The resulting solution isstirred for one hour at 25 C. and then allowed to stand at 25 C. forfour-hours. The solution is then poured in a thin film onto a glassplate and the water allowed to evaporate at room temperature. Unreactedethanolamine is extracted with methanol from the viscous syrup whichremains and the resulting product is dried at 60 C. for six hours. Thehard brittle copolyamide thus obtained is insoluble in dimethylformamideand chloroform, and soluble in water, formic acid, dichloroacetic acid,and m-cresol, exhibiting an 71inh.:0.08 in the latter. Nitrogen analysisindicates the polyamide to contain 15.86% nitrogen. The theoreticalvalue for the complete conversion of all the extralinear carbomethoxygroups to hydroxyethylcarbamyl groups (i. e., a polyamide of molecularformula CeH1oN2O3), is 17.71% nitrogen. These results indicate theproduct to be a 73/27 copolyamide from DL-beta-(hydroxyethylcarbamyl)alphaaminopropionic acid/DL beta carbomethoxyalpha-aminopropionic acid.

EXAMPLE VIII Another two-part sample of the same polyamide from DL betacarbomethoxy alphaaminopropionic acid (described in the twoprecedingexamples) is added portionwise over a period of two to three minutes toa stirred solution of 9.3 parts of 25% aqueous methylamine in 50 partsof water. The resulting solution is stirred for one hour at 25 C.,allowed to stand for five hours at this temperature, and finally pouredin a thin film onto a glass plate. Water and unreacted methylamine areallowed to evaporate at room temperature. The clear, brittle copolyamidefilm thus obtained is insoluble in'chloroform and dimethylformamide andsoluble in formic acid, methanol, acetic acid and m-cresol (all at steambath temperatures) and exhibits an 77inh.:0.09 in the latter. Nitrogenanalysis of the copolyamide indicates it to contain 20.11% nitrogen. Thetheoretical value for the complete conversion of all the extralinearcarbomethoxy groups to N-methylcarbamyl groups (i. e., a copolyamide ofmolecular formula CsHaNzOa), is 21.88% nitrogen. These results indicatethe product to be an 84/16 copolyamide from DL- beta-N-methylcarbamylalpha aminopropionic acid/DL-beta-carbomethoxy alpha aminopropicnicacid.

EXAMPLE IX DL-beta-N-dodecylcarbamyl alpha aminopropicnic acid/DL betacarbomethoxy-alphaaminopropionic acid copolyamide The solid is broken'upand the suspension warmed to the boiling point of the ether and theetherthen decanted from the residual material. This process is again repeatedand 200 parts of distilled water then added to the remainingprecipitate. The suspension is warmedto 'lll" and the product removed byfiltration. 'Ait'er air drying, there is obtained 20.4 parts (83% yield)of copolyamide. This material is soluble in (ii-- chloroacetic acid,m-cresol, and chloroformall at steam bath temperatures. Strong', selfsupporting films can be obtained from solutions of the copolyamide inthese solvents by standard film casting procedures.

Carbon analysis of samples of this material indicate the copolyarnide tocontain an average or 67.3% carbon. The theoretical value for corn--plete conversion of the extralinear carbomthoxy groups toN-dodecylcarbamyl groups (i. e., apolyamide of empirical formulaC16H3002N2) is 681% carbon. The starting DL betacarbomethoiiyalpha-aminopropionic acid homopolyamide (l. e., a polyamideof empirical formula CsI-IwQaN) contains 46.5% carbon. From these data,it is calciilated that the product is a 96.8/3.2 copolyafnide 'fro'mDL-beta-N-dodecylcarbamyl-alpha-aminopropionicacid/DL-carboinethoxy-a1pha-aminopropionic acid.

The preparation of DL-beta carbomethoxyalpha-aminopropionic acid and itsN-carboanhydride have been given in Example I-A and 1-3, respectively,with certain reaction conditions of time and temperature andpropcrtions. However, the reaction conditions can be varied considerably and other methods may be employed.

Thus, there can be employed for the preparation of theDL-beta-carboalkoxy and carboaralko'xyalpha-aminopropionic acids andtheir hydrohalide derivatives the method of Wegscheider diethyl ether. AWater solution of-the ether eit- "tr'acted product is then treated withan aqueous solution of copper acetate, the mixture evaporated, and theresidues triturated with cold waterand the solid removed byfiltrationand carefully "Water washed.

The aqueous "filtrate is then treated with hydrogen sulfide and theprecipitated copper sulfide removed by filtration. This filtrate in turnis concentrated and the DL-betacarboethoxy-alpha-aminopropionic acidprecipitated with alcohol and removed by filtration.

Furthermore, the N-carboanhydrides of these DL beta carboalkoxy alphaamihopropionic acids can be prepared as is disclosed in U. S.

Patent 2,516,145 by treating the requisite alphaamino acid in ananhydrous solvent with an alkali .rnetal alkoxide and with carbondioxide thereby forming the dialkali metal salt of thealphacarboxy-aminocarboxylic acid, reacting thionyl "chloride with thissalt, and finally isolatin gthe desired N-carboanhydride.

- The N-carboanhydrides of the Dll beta'carboalkoxy-alpha-aminopropionic acids can also be prepared as isdisclosed in the copending applications of MacDonald filed October 7;1947-; Ser.

:No. 778,458, and March 24, 1949, Ser. No. 83,299, by reacting thedesired alpha-amino acid or its alkali metal or alkaline earthmetal-salts with xphosgene under anhydrous conditions. These N- iiflylchlbrid'e Under amide-- aminopmpiomc ihg increase in polymers contain asubstituted tuthcse of DP of "50 to carbo'anhydrides can also beprepared by'the 'in'ethod disclosed in the copending applicationofPrichaid filed October 5, 1948, 'Ser. N0.'52,971, by reacting the aminoacid or it's alkali metal, alkaline earth metal or hydrohalide saltswith phcsgene under anhydrous conditions in the presence of an ether.This method is particularly exemplified for DL beta carbomethoxyalphaamincpropiomc acid hydrochloride in Example I, Part B. l i

' These N-carboanhydride intermediates can also be prepared Iromthecor-responding amino acids as reported by Leuchs, Ber. 39, 857 (1906),by reacting the amino acid with a haloformate,

particularly a chloroformate, ester, isolating the ester of theN-carboxyami no acid so formed, subsequently reacting this derivativewith thianhydrous conditions, and isolating the desiredN-carboanhydride. In mate of "thionyl chloride in the above reactionsystem, there may be used other halogenatin'g agents, such as phosgene,phosphorus pentachlo'ride, phosphorus trichlori'de, phosphorusbiiychloiide and the like, as described in U. S. Patents 2,327,162 and2,406,816.

This invention is generic to the alpha-amino acid polya'mides containingfrom 2 to coinbined alpha-carbonar'nidoand alphasubstituted-carbonamidomethylglycine units, 1. "e., beta carbori'amid'oand substituted "carbonammo-alphaaminopropiomc acid units. When "atleast 2% or the recurrin alpha-aminocarboxylic acid units bf thepolyainid's of this invention are composed of these residues, thepolyainide is capable of controllable modificamm in its generalsolubility properties, particularly in its degree of response to aqueousprocess ing' treatments through chemical modification effected throughreactions with the extralinear carbon'amido and substituted-carbona-midogroups, usually through the amide hydrogens of such groups.

As the proportion of combined beta-carbohandsubstituted-carbonamido-a1bhaacid units in the polyamides of thisinvention increases, were is a correspondthe above-described capabilityof being controllably modified in properties and also in the solubilitybehavior of the polymers. This becomes particularly noticeable when themajor proportion,-i, e., more than 50% of the DLbeta-'-carbonamido and acarbon'amido alpha aminopropichic acid limits. The polyamides of thisinvent-ion differ rather markedly not only as the pro- "portion ofcombined beta-carbonamidoand substituted carbonamido alphaaminopropionic acid units in the polyamides increases, but also as themolecular weight, or, more factually used, degree of polymerization(DP), increases. This invention, as has been pointed out preyiously, is"generic to those polyamides containmg from 12 to 100% combined betacarbona'r'nidm and substituted-carbonamido-alphaamihopropionic acidunits. It is also generic to these poiyamicies of DP varying from 10 to20 a n 100 or higher. These pclyam aes 'obvidusly difie'r quite markedlyin physical properties and, as such, are useful in man'y'fields.

More "specifically, the Dolyaniides of this inveiitien "of 10W DPS 0fthe order or 10 to 2G, and generally appreciabl less than 50, are usefulas permanent antistatic finishes, casein re lacememe, thickening agents,adjuvants for electroplating baths and the like. generally preferredthat the In'these uses it is polymers contain major proportions, e. g.,greater than 50%, of combined DL-beta-carbonamidoand substi- .tuted DLbeta carbonamido alphaaminopropionic acid units.

On the other hand,

for such uses as gelatin substitutes, those poly- -mers of higher DPfrom 20 to 50 and preferably nearer 50 and containing again majorproportions of, e. g., greater than 50%, combined, DL-beta-carbonamidoand'substituted-DL-betacarbonamido-alpha-amino-propionic acid units arepreferred. Another important use, wherein the polyamides of low DP, 1.e., those of the order of 10 or perhaps slightly lower, are outstanding,is in the field of biologically active compositions. In this use thosepolyamides of this invention containing appreciable quantities,

i. e., from to 50% of combined DL-betacarbonamidoandsubstituted-BL-beta-carbonamido-alpha-aminopropionic acid units arepreferred.

On the other hand, for film and fiber use, those polyamides of thisinvention of'the higher DPs of at least 50 and preferably higher arepreferred. In such uses, the preferred combined pecentage ofDL-beta-carbonamidoand substituted DL beta carbonamido alphaaminopropionic acid units varies with the properties desired in the filmor fiber. For instance, if

very high degrees of water absorptions aredesired, those polyamidescontaining relatively high proportions of combinedDL-beta-carbonamidoandsubstituted-DL-beta-carbonamidoalpha-aminopropionic acid units are used.If

moderate degrees of water absorption are desired, those polyamides ofthis invention containing largely minor, e. g., 2 to proportions ofcombined DL-beta-carbonamidoand substituted DL beta carbonamidoalphaaminopropionic acid units are used.- In this connection, it shouldbe pointed out that the variation in per cent water absorption varies.linearly with per cent combined DL-beta-carbonamidoand substituted -'DLbeta carbonamido-alpha-aminopropionic acid'units. On the other hand, forpreparing films and fibers of vastly-different solubility behavior,those polyamides of this invention containing a very small amount ofcombined alkylene-bis(carbonamidomethyl) links are particularly useful,i. e., those prepared from diamines.

-As stated previously, the polyamides of this invention contain combinedbeta-carbonamidoalpha-aminopropionic acid units wherein the amidenitrogens of the extralinear carbonamido groups carry hydrogen orhydrocarbon radicals, or wherein said nitrogens are annular members ofheterocycles which can contain additional heteroatoms, i. e., oxygen,nitrogen, or sulfun A particularly preferred group of the polyamides ofthis invention contain :combined betacarboalkoxyor carboaralkoxy alphaaminopropionic acid units in addition to the abovedescribedbeta-carbonamidoand substitutedcarbonamido-alpha-aminopropionic acidunits.

The most convenient way of preparing the extralinear carbonamido andsubstituted-carbonamido containing polyamides of this invention is topolymerize the amide-forming 'de-,

rivatives, particularly the N-carboanhydrides, of the desired esterifiedbeta carboxyandparticularly the beta-carboalkoxy-alpha-aminopropionicacids either alone or with the amide-formmg derivatives, againparticularly theN-carbo yaniline, 2-(4 hydroxyphenyl) ethylamine;

anhydrides, of other alpha-aminocarboxylic acids. The polyamide orcopolyamide thereby obtained is then reacted with the desired primary orsecondary amine or ammonia until the required aount of extralinearcarboalkoxymethyl groups are converted to the desired carbonamido- -orsubstituted-carbonamidomethyl groups. Re-

action with amino-hydrogen-containing amines is preferred. It isnecessary that about 1% of these extralinear carboalkoxymethyl groups beso converted in order that the final polyamide will have propertiedifferent from the starting polyamide containing extralinearcarboalkoxymethyl groups.

Examples of the primary and secondary monoor diamines which can be usedin reaction with the preformed DL betacarboalkoxymethylalpha-aminopropionic acid polymers to form thepolyamides of this invention are amino-hydrogen-containing amines, e.g., primary aliphatic amines, e. g., methylamine, ethylamine, amylamine,dodecylamine; secondary aliphatic amines, e. g., dimethylamine,diamylamine, ethylpropylamine; primary aromatic amines, e. g.,beta-naphthylamine and p-methylaniline; secondary aromatic amines, e.g., diphenylamine, N- ethylaniline, N-butylaniline; primaryaliphaticaromatic amines, e. g., 2-phenylethylamine, 3-phenylpropylamine; secondary aliphatic-aromatic amines, e. g.,di-Z-phenylethylamine and ethyl-2-phenylethylamine; substituted primaryaliphatic amines, e. g., 2-chloroethylamine, 3- nitropropylamine,4-ethoxybutylamine, l-phe- ,noxy-G-aminohexane; substituted secondaryaliphatic amines, e. g., N-2-chloroethylethylamine, N methyl 3nitropropylamine, N methyl-2- phenoxyethylamine, N-ethyl 2methoxyethylamine; substituted primary aromatic amines, e. g.,4-nitroani1ine, 3-chloroaniline, Z-ethylaniline,4-ethoxy-2-chloroani1ine, 3,5-diethylaniline, 4-aminodiphenyl ether;substituted secondary aromatic amines, e. g., N-methyl-p-chloroaniline,N-phenyl-p-nitroaniline, N-ethyl-p-phenetidine; substituted primaryaliphatic-aromatic amines, e. g., 2-(4-chlorophenyl)ethylamine,3-(3-nitrophenyDpropylamine; substituted secondary aliphatic aromaticamines, e. g., N-methyl-2-(4- chlorophenyl) ethylamine, N-ethyl-3-(4-ethoxyphenyl) propylamine; primary cycloaliphatic amines, e. g.,cyclohexylamine and Z-aminodecahydronaphthalene; secondarycycloaliphatic amines, e. g., dicyclohexylamine andN-methylcyclohexylamine; substituted primary cycloaliphatic amines, e.g., 4-nitrocyclohexylamine, 3- chlorocyclohexylamine; substitutedsecondary cycloaliphatic amines, e. g.,N-methyl-i-chlorocyclohexylamine, N ethyl-4-ethoxycyc1ohexylamine;polyamines, e. g., ethylenediamine, hexamethylenediamine,N,N-diethylethylenediamine, p-phenylenediamine, N-2-chloroethyl-N-ethylylenetetramine; cyclic amines, e. g., piperidine, piperazine,2,5-dimethylpiperazine, morpholine; heterocyclic amines, e. g.,alpha-aminothiophene, 2-aminothiazole, 2-amino-4-methylthiazole, and2-aminopyridine; hydroxy-containing amines, e. g., 2-hydroxyethylamine,4-hydroxymethylaniline; mercapto-containing amines, e. g., 2-mercaptoethylamine, 4 (2 mercaptoethyl) -2- methylan'iline; phenolicamines, e. g., 4-hydroxyhydrazines, e. g., hydrazine, Z-propylhydrazine;guanidines, e. g., guanidine, N-phenylguanidine; biguanides, e. g.,biguanide, N-phenylbiguanide. In the case of the above-mentioneddiamines.

17 the resultant polyamide will, of course, be crosslinked to the extentthat the respective diamine reacts under the conditions used-said crosslinks consisting of the diamine fragment bond ing two extralinearcarbonamido groups. These crosslinked compositions are of particularinterest in fiber outlets.

Because of their greater reactivity, aliphatic,

i. e., nonaromatic, amines, both monoand ,di amines, are preferred, Inthe case of the arcmatic amines, since amidation is relatively dinicultto accomplish, rather vigorous reaction conditions are preferablyemployed. Because of the undesirable side reactions encountered whenrelatively high reaction temperatures are employed, it is preferred tocarry out the amidation with aromatic amines using sodamide or otherstrongly basic metal ammonia or metal ,amine compounds and the desiredaromatic amine in the manner of Jacobson, J. Am. Chem. $00., 6 7, 1998(1945).

As has been stated previousl the polyamides of this invention can beconveniently prepared by polymerizing the amide-forming derivatives,preferably the N-carboanhydrides, of beta-earboalkoxyandcarboaralkoxy-.alpha-,aminopropicnic acids, either alone or with theamideforming derivatives (again preferably the N-carboanhydrides) ofother valpha-aminocarboxylic acids, preferablyalpha-monoa-mino-monoearboxylic acids, and to react the thus formedpolymer with ammonia or the requisite primary or secondary amine neededto convert the extralinear .carboalkoxy groups to the desiredcarbonamido or substituted carbonamido groups. The amide-formingderivatives of any beta-carboalkoxy -alpha-aminopropionic acid can beused. As illustrated in Example I, Part A, thesebetacarboalkoxy-alpha-aminopropionic acids can be conveniently preparedby methods known in the art.

While the linear polyamides, having .e-xtralinear .carbonamidesubstituents, of this invention may be made from linear polyamideshaving extralinear .oarboaralkoxy, e. e., carbo nzy oxy, substituents,the greater reactivity of the linear polyamides having extralinearcarboxyl groups esterified with lower .alkanols, i..e., of one to fourcarbons, is such as to render these latter the really practical polymer:raw materials for the present invention although the invention isgegneric to the preparation of polyamides having .extralinearcarbonamide substituents and their preparation from linear polyamideshaving extralinear carboxyls esterified by mohohydric alcoholshydrocarbon except for :the alcoholic hydroxyl. Because of superiorreactivity with ammonia and primary and secondary amines in forming theside chain carbonamido and substituted carbonamido groups,DL-beta-carbomethoxy-alpha-aminopropionic acid is especially preferred.

Although, as has been stated previously, this invention is generic tothe alpha-amino acid polyamides containing from about 1 to 2 to 100%combined alpha-carbonamidoandsubstitutedcarbonamido-alpha-aminopropionic acid units,

the preferred polyamides are those containing from about 1 .to 2 to 100%substituted-carbonamido-alpha-aminopropionic acid units, 1. e.,alpha-amino acid polyamides containing from about 1 to 2 .to 100%combined beta-carbonamido-alph,a-aminopropionic acid units, wherein theamide nitrogens of the extralinear carbonamido groups carry hydrocarbonradicals .or ,at

groups, are much preferred over those containing the extralinearcarbonamido, i. e., carbamyl groups, because the former exhibitgenerally better organic solvent solubility in a wider range ofsolvents. This solubility difference becomes more particularlypronounced as the percentage of combined beta-carbonamidoandsubstitutedcarbonamido-alpha-aminopropionic acid units in the polyamidesincreases and also with increasing carbon content of the radicals bondedto the amide nitrogens in the extralinear carbonamido groups.

As has been pointed out in Example I, Part D, representative polymers ofthis invention containing appreciable proportions of combinedbeta-carbamylealphaeaminopropionic acid units are soluble only in waterand strong organic acids, e. g, formic and dichloroacetic acids andinsoluble in a wide variety of organic solvents. From the point of viewof convenience and the desirability of handling, the strong organicacids are not desirable solvents, to say nothing of the quality and cost.of the equipment needed to handle them. Furthermore, as also indicatedin this example, water solutions, which would, of course, be acceptablefrom the solvent standpoint, are extremely viscous-thus making itdifficult to carry out normal film casting and fiber spinningprocedures.

On the other hand, as pointed out in the other examples, those polymersof this invention wherein the extralinear carbonamido groups carry oneor two alkyl or cycloalkyl hydrocarbon radicals on the amide nitrogensare soluble in a wide variety of the common organic solvents and exhibitnormal viscosities in such solvents. Solutions of these polyamides insuch solvents can be readily and conveniently used in normal filmcasting and fiber spi ning procedures.

In the case of copolymers containing the combined residues of otheralphaeaminoearboxyllc acids there are, of course, additional units inthe polymer chain other than the combinedDL-betacarboalkoxy-alpha-aminopropionic acid units and L-bet -car onamdo o u st dbonarnido alpha arninopropionic acid units.

HOW 111 0 1 hydrolysis with hydrochloric acid,

the polyamides .of this invention yield alphaarnino-carboxylic acidhydrochlorides at least 2% andpreferably 5% of which isDL-beta-carboxy-alpha-aminopropionic acid hydrochloride, .due toconcomitant hydrolysis of the lateral carjbonamido groups.

Alpha monoaminomonocarboxylic acid N-carboanhydrides in general can becopolymerized with the DL-betaecarboalkoxy-alpha-aminopropi ni a d -caoa h r d s to r c p lramides which can be converted into thecopolyamides ,of this invention by reaction with am- ,rno 'lia or aprimary or secondary amine, including. f r example aloha-primar -m am n-alkanoic Qi'iS .6- u l c n al n n em 1 leu in ,pseudo eu n .n leu i e vl ne no yaline, alphaaminoenwbutyric acid, alphamethyl alphaamino e nbutyric acid, alpha- .amino-neheptanoic acid, alpha-arnino-n-octanoicacid, alpha-amino-lauric acid, alpha-air ine- .rnyr-istic acid,.alpha-aminoisobutyric acid, alphaa phaeami oi omn b methylglycine,N-isopropylglycine, N-butylglycine, N-octadecylglycine,N-isopropylleucine, l methylalanine.

The polyamides and copolyamides of this invention are preparedoptionally in the presence of organic liquids by the condensationpolymerization (thermal or initiated by water, alcohols, phenols,organic acids, or amino-hydrogen-containing amines) of the previouslydefined monoaminomonocarboxylic acid N-carboanhydrides with carbondioxide evolution. Suitable organic liquids that can be used includearomatic hydrocarbons, e. g., benzene, xylene; halogenated hydrocarbons,e. g., chloroform, chlorobcnzene, tetrachloroethane, carbontetrachloride; alicyclic ketones, e. g., cyclohexanone; hydrocarbonetherc,

e. g., anisole and dibutyl ether.

The N-carboanhydrides are suitably heated in a vessel adapted to permitthe escaping of carbon dioxide to that temperature at which carbondioxide begins to be evolved at an appreciable rate under the conditionsof reaction. This varies with different amino acids, but it is usuallyin the range from 25 to 200 C. and generally within 30-50 C. of themelting point of the lowest melting N-carboanhydride present in themixture to be polymerized. The time of the reaction can be shortened orthe temperature can be lowered or both can be accomplished by the use ofreaction initiators, e. g., water, alcohols,

phenols, and selected organic acids or aminohydrogen-containingamines-the latter two as disclosed in the copending applications of Mac-Donald, Ser. Nos. 778,031 and 778,032, filed Octoher i, 1947.

The reaction of the intermediate alpha-amino acid polyamides andcopolyamides containing extralinear esterified carboxyl groups, e. g.,carboalkoxymethyl groups, with the primary and secondary monoor diaminespreviously discussed to form the polyamides and copolyamides of thisinvention containing at least 2 and preferably at least 5% extralinearcarbonamidoand substituted-carbonamidomethyl groups can be carried outunder a wide variety of conditions. For instance, the amine reactant maybe used in sufiicient excess quantities to serve as a solvent orsuspension agent for the polyamide or copolyamide being reacted. Inertorganic liquids may be used as reaction media. Of these it is preferredto use those which are solvents for the intermediatecarboalkoxymethyl-containing polyamides and copolyamides. Particularexamples of such solvents are water, halogenated hydrocarbons such aschloroform, carbon tetrachloride, tetrachloroethane, and chlorobenzene;aromatic hydrocarbons such as benzene, toluene and the xylenes.

The reaction may be carried out under superpressures which is preferablydone in those cases where the amine reactants are normally gaseous.

The reaction temperatures may vary from -78 C. to +150 C. depending ingeneral on the reactivity and physical constants of the amine reactantsinvolved. For instance, if the amine is one which is normally gaseous,then the reaction temperatures used are preferably in the lowestpossible range commensurate with appreciable reaction. On the otherhand, if the amine reactants are relatively high boiling-preferablyliquidsthe reaction temperatures may be conveniently those at which theamine reactant boils under normal conditions, i. e., the reaction iscarried out at the reflux. In the case of those amine reactants whosenormal boiling points are intermediate between room temperature and70-100 C., as well as those amine reactants normally above 150 C., thereaction is usually carried out using an inert organic solvent andusually in the range of to 100 C.

The time of reaction may vary from as little as five to ten minutes toas long as is desired. For minimum conversion of the amount ofextralinear carboalkoxymethyl groups in the intermediate polyamides andcopolyamides to engender the necessary diiference in properties in theend product extralinear carbonamidoandsubstituted-carbonamidomethyl-containing polyamides, it is usuallynecessary that the reaction be carried out for at least to minutes.Obviously as the time of reaction increases, the amount of amidationlikewise increases.

The polyamides and copolyamides of this invention, i. e., thosecontaining a plurality of combined beta-carbonamido-alpha-aminopropionicacid units can be prepared directly in situ in the desired form, e. g.,films or fibers. This is most conveniently done by forming the preferredintermediate beta-carboalkoxy-alpha-aminopropionic acid polymer directlyin the presence of ammonia or the desired primary or secondary amine andsubsequently carrying out the desired conversion of the extralinearcarboalkoxy groups to the required carbonamido and substitutedcarbonamido groups. This is particularly applicable in the case offibers especially for the crosslinked fibers obtained by using diprimaryor disecondary diamines.

More specifically, the desired polyamide containing a plurality ofcombined beta-carboalkoxy-alpha-aminopropionic acid units (easilyprepared and in high molecular weight as discussed previously andserving as an intermediate in the preferred route to the polyamides ofthis invention) is formed into fibers, i. e., spun into a coagulatingbath, e. g., water or methanol, and then pased through a bath containinga solution of the desired diamine, e. g., hexamethylenediamine with thediamine bath maintained at sufficiently high temperature, e. g., from toC., and with the fiber throughput at such a speed that the fiber ismaintained in this diamine bath at the reaction temperature for from 10to 60 minutes. The thus formed crosslinked fiber after washing andnormal yarn processing produces fibers possessing a plurality ofhexamethylene bis carbonamidomethyl crosslinks. The same results may beachieved by forming the beta-carboalkoxy-alpha-aminopropionic acidpolyamide directly in fiber form in a coagulating bath containing thedesired diamine and maintaining the fiber in the bath for a sufficienttime to carry out the desired crosslinking reaction. Similarly, thedesired fiber can be prepared by forming the startingbeta-carboalkoXy-alphaaminopropionic acid polyamide into fiber formgiven for clearness of understanding only and.

no unnecessary limitations are to be understood therefrom. The inventionis not limited to .the

exact details shown and described for obvious modifications will occurto those skilled in the.

art.

What is claimed is:

1. Anoptically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially ofDL-betaoarbomethoxy-alpha-aminopropionic acid units andDL-beta-carbonamido-alpha-aminopropionic acid units wherein thevaiencesof the extralinear carbonamido nitrogen not bonded to thecarbonyl group are bonded to radicals forming, to gether with NH, anorganic amine.

2. An optically inactive copolyamideofdegree of polymerization of atleast 50, the recurring units of which consist essentially ofDL-beta-car bomethoxy-alpha-aminopropionic acid unitsand DL betacarbonamido alpha-aminopropionic acid units wherein the valences of theextralinear carbonamido nitrogen not bonded .to the carbonyl group arebonded to hydrocarbon radicals.

3. An optically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially ofDL-betacarbomethoxy-alpha-aminopropionic acid units andDL-beta-carbonamido-alpha-aminopropionic acid units wherein theextralinear carbonamido nitrogen is an annular member of a heterocyclicring.

4. An optically inactive polyamide of degree of polymerization of atleast 10, the recurring units of which are alpha-monoaminomonocarboxylicacid units from 1 to 100% of which are DL beta carbonamidoalpha-arhinopropionic acid units wherein the valences of the extralinearcarbonamido nitrogen not bonded to the carbonyl group are bonded toradicals of the class consisting of hydrogen, hydrocarbon radicals andradicals which, together with said amido nitrogen form a heterocyclicring.

5. An optically inactive polyamide of degree of polymerization of atleast 10, the recurring units of which are alpha-monoaminomonocarboxylicacid units from 1 to 100% of which areDL-betacarbonamido-alpha-aminopropionic acid units wherein the valencesof the extralinear carbonamido nitrogen not bonded to the carbonyl groupare bonded to radicals forming together with NH an organic amine.

6. Process for the preparation of optically inactive polyamides, therecurring units of which are alpha-monoaminomonocarboxylic acid unitsfrom 1 to 100% of which are beta-carbonamidoalpha-aminopropionic acidunits which comprises bringing an optically inactive polyamide of degreeof polymerization of at least 10, the recurring units of which arealpha-monoaminomonocarboxylic acid units from 2 to 100% of which arebeta-carbomethoxy-alpha-aminopropionic acid units in contact with anitrogen compound of the class consisting of ammonia and primary andsecondary amines until at least 1% of the carbomethoxy groups areconverted to carbonamido groups.

7. Process for the preparation of optically inactive =polyamides, "therecurring units of which are alpha-monoaminomonocarboxylic acid unitsfrom 1 to of whichare beta-carbonamidoalpha-aminopropionic acid unitswhich comprises bringing an optically inactive polyamide of degree ofpolymerization of at least 10, the recurring units of which arealpha-monoaminomonocarboxylic acid units from 2 to 100% of which arebeta carboalkoxy alpha aminopropionic acid units in contact with anitrogen compound of the class consisting of ammonia and primary andsecondary amines until at least 1% of the carboalkoxy groups areconverted to carbonamido groups.

8. Process for the preparation of optically inactive polyamides, therecurring unit of which.

are alpha-monoaminomonocarboxylic acid units from 50 to 100% of whichare beta-carbonamidoalpha-amin-opropionic acid units which comprisesbringing an optically inactive polyamide of degree of polymerization ofat least 10, the recurring units of which arebeta-carboalkoxy-alphaaminopropionic acid units wherein the alkyl of thecarboalkoxy group is from one to six carbons, in contact with a nitrogencompound of the class consisting of ammonia and primary and secondaryamines until at least 1% of the carboalkoxy groups are converted tocarbonamido groups.

9. Process for the preparation of optically inactive polyamides, therecurring units of which are alpha-monoaminomonocarboxylic acid unitsfrom 50 to 100% of which are beta-carbonamidoalpha-aminopropionic acidunits which comprises bringing an optically inactive polyamide of degreeof polymerization of at least 10, the recurring units of which arebeta-esterified carboxylalpha-aminopropionic acid units, in contact witha nitrogen compound of the class consisting of ammonia and primary andsecondary amines until at least 1 of the esterified carboxyl groups areconverted to carbonamido groups.

10. Process for the preparation of optically inactive polyamides, therecurring units of which are alpha-monoaminomonocarboxylic acid unitscomprising beta-carbonamido-alphaaminopropionic acid units whichcomprises bringing an optically inactive polyamide of degree orpolymerization of at least 10, the recurring units of which arealpha-monoaminornonocarboxylic acid units from 2 to 100% of which arebeta-carbomethoxy-alpha-aminopropionic acid units in contact with anitrogen compound of the class consisting of ammonia and primary andsecondary amines and continuing the treatment until the solubilityproperties of the initial polyamide are substantially changed byconversion of carbomethoxy units to at least 1% of the carbonamidounits.

11. Process of claim 10 wherein the nitrogen compound is a primaryamine.

12. Process of claim 10 wherein the nitrogen compound is a diprimarydiamine.

13. Process of claim 10 wherein the nitrogen compound is a primarymonoamine.

14. Process of claim 10 wherein the nitrogen compound is a secondaryamine.

15. An optically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially of DL-beta-carbomethoxy-alpha-aminopropionic acid units andDL-beta-carbonamido-alpha-aminopropionic acid units wherein the valencesof the extralinear carbonamido nitrogen not bonded to 23 the'carbonylgroup are bonded to radicals forming, together with NH, a primary amine.

16. An optically inactive polyamide of degree of polymerization of atleast 50, the recurring units of which are alpha-monoaminoinonocar--boxylic acid units from 1 to 100% of which are DL-beta-carbonamido alphaaminopropionic acid units wherein. the valences of the extralinearcarbonamido nitrogen not bonded to the carbonyl group are bonded tohydrogen.

17. An optically inactive polyamide of degree of polymerization of atleast 50, the recurring units of which are alpha monoaminomonocarboxylicacid units from 1 to 100% of which are DL-beta-carloonamido alphaaniinopropionic acid units wherein the valences oi the extra linearcarbonamido nitrogen not bonded to the carbonyl group are bonded toradicals forming, together with an organic amine.

18. An optically inactive polyamide of degree of polymerization of atleast 50, the recurring units of which arealpha-"nonoaininomonocarboxylic acid units the major proportion of whichare DL-beta carbonamido alpha aininopropionic acid units wherein thevalences of the extralinear carbonamido nitrogen not bonded to thecarbonyl group are bonded to hydrogen.

19. An optically inactive polyamide of degree of polymerization of atleast 50, the recurring units of which are alpha-nionoaininoinonocarboxylic acid units the major proportion of which areDL-beta-carhonarnido-alpha aininopropionic acid units wherein thevalences of the extralinear carbonamido nitrogen not bonded to thecarbonyl group are bonded to radical forming, together with NH, anorganic amine.

20. An optically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially of DL- betacarboalkoxy alpha aminopropionic acid units andDL-beta-carbonamido-alpha-aminopropionic acid units wherein the valencesof the extralinear carhonamido nitrogen not bonded to the carbonyl groupare bonded to hydrogen.

21. An optically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially of DL- betacarboalkoxy alpha aminopropionic acid units andDL-beta-carbonamido-alpha-aminopropionic acid units wherein the valencesof the 24 extralinearcarloonamido nitrogen not bonded to the carbonylgroup are bonded to radicals forming, together with NH, an crganicamine.

22. An optically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially of DL betacarbomethoxy-alpha-aminopropionic acid units and, in major proportion,DL-betacarbonamido-alpha-aminopropionic acid units wherein the valencesof the extralinear carbonamido nitrogen not bonded to the carbonyl groupare bonded to hydrogen.

23. An optically inactive copolyamide of degree of polymerization of atleast 50, the recurring units of which consist essentially of DL betacarbomethoxy-alpha-aminopropionic acid units and, in major proportion,DL-betacarbonamido-alpha-aminopropionic acid units wherein the valencesof the extralinear carbonamido nitrogen not bonded to the carbonyl groupare bonded to radicals forming, together with NH, an organic amine.

24. Process for the preparation of optically inactive polyamides, therecurring units of which are alpha-monoaminomonocarboxylic acid unitsfrom 50 to of which are beta-carbonamidoalpha-aminopropionic acid unitswhich comprises bringing an optically inactive polyamide of degree ofpolymerization of at least 10, the recurring units of which arebeta-esteriiied carboxyl-alpha-aminopropionic acid units, in contact,dispersed in an inert organic liquid, with a nitrogen compound of theclass consisting of ammonia and primary and secondary amines until atleast 1% of the esterified carboxyl groups are converted to carbonamidogroups.

MAYNARD S. RAASCH. CHARLES W. TULLOCK.

References Eiterl in the file of this patent Fraenkel-Conrat et al.:Journal American Chemical Society, vol. 67, pages 950 to 954, 1945.

Frankel et al.: Nature, vol. 163, pages 213, 214, February 5, 1949.

Fischer et al.: Berichte der Deutsche Chemische Gesellschaft, vol. 40,1907, pages 2048, 2049, 2057, 2058, 2060, 2061.

Bergmann et al.: Berichte der Deutsche Chemische Gesellschaft, vol. 66,pages 1288, 1289, 1933.

4. AN OPTICALLY INACTIVE POLYAMIDE OF DEGREE OF POLYMERIZATION OF ATLEAST 10, THE RECURRING UNITS OF WHICH ARE ALPHA-MONOAMINOMONOCARBOXYLICACID UNITS FROM 1 TO 100% OF WHICH ARE DL - BETA - CARBONAMIDO -ALPHA-AMINOPROPIONIC ACID UNITS WHEREIN THE VALENCES OF THE EXTRALINEARCARBONAMIDO NITROGEN NOT BONDED TO THE CARBONYL GROUP ARE BONDED TORADICALS OF THE CLASS CONSISTING OF HYDROGEN, HYDROCARBON RADICALS ANDRADICALS WHICH, TOGETHER WITH SAID AMIDO NITROGEN FORM A HETEROCYCLICRING.